Pirelli Cinturato Gravel M Tire - 650b x 45 Tubeless Folding BlackPirelli Cinturato Gravel M Tire 650b x 45 Tubeless Folding Black. The Cinturato Gravel M (Mixed Terrain) is a gravel specific tire designed for mixed terrain where the surface varies between compact and unstable terrain and all intermediate types. The tread consists of knobs with average height and spacing to guarantee excellent performance on a wide range of terrains. SpeedGRIP Compound adds features of mechanical resistance and chemical grip without